"The simple answer is that there is no work being done on an online version of the original Halo. The resources that would be needed to do this justice would have a negative impact on how much cool stuff we could do for Halo 2. As such, a decision was made to focus solely on Halo 2 for next year, and believe me, it's the right decision.

It's not possible to add Xbox Live support to a title that didn't support it when initially released. The ability to update a title at all is something that comes with Live enabling."